Cutting insert and cutting tool assembly

ABSTRACT

The cutting tool assembly of the present invention consists essentially in (a) a tool holder and (b) an indexible cutting insert of modified rhombic configuration in which pairs of main cutting edges (disposed at an angle of less than 60* with respect to each) are separated by intermediate facing edge portions which are parallel to each other. The intermediate facing edge portions are so configured as to constitute outfacing cutting edges each of which cooperates with the main cutting edge adjacent thereto. Both the pairs of main cutting edges and the out-facing cutting edges are provided with chip-breaking grooves. The assembly provides an arrangement wherein not only the main cutting edge but also the out-facing cutting edge of the cutting insert are laid bare with respect to the tool holder.



1. A copy turning indexible cutting insert having cutting tip angles below 60*, the cutting insert 11 being basically of rhombic configuration and having edge portions 21, 22 which separate the edges 17, 18, 19, 20 extending towards the cutting tips and which extend symmetrically relative the longest diagonal and substantially parallel thereto, at least one of two edges extending to one cutting tip being formed as a main cutting edge and the insert having substantially flat side surfaces 12, 13 being located at a right angle at the intersection of the edge surfaces, 14, 15, 16, characterized in that each of said parallel edge portions 21, 22 is formed as an out-facing cutting edge for co-operation with the main cutting edge 18, 19 located adjacent thereto, and said main cutting edges and said outfacing cutting edges being provided with chip breaking grooves 39, 40 said insert being adapted for engagement in a recess in a tool holder in such a manner that the edge forming the main cutting edge as well as the out-facing edge located adjacent thereto are laid bare with respect to said holder.
 2. A cutting insert according to claim 1, characterized in that the main cutting edges 18, 19, 43 and said edge portions 21, 22, 44 are located substantially beneath associated flat side surfaces 12, 13, each main cutting edge being located substantially in one plane which passes through the cutting tip 26, 28 associated with the main cutting edge and forms an angle with the flat side surface associated with the main cutting edge.
 3. A cutting insert according to claim 1, characterized in that the width and depth of the cutting chip breaking grooves 39, 40, increase in depth and width from the cutting tip end 26, 28 of each main cutting edge 18, 19, 43 to the junction point of said cutting tip end with the associated edge portion 21,
 22. 4. A cutting insert according to claim 1, characterized in that the chip breaking grooves 39, 40, 72 adhere on to the cutting edges via a flat bevel
 73. 5. A cutting insert according to claim 1, characterized in that all edge surfaces 14, 15, 16 of the insert extend substantially tangentially to a circle inscribed in the basically rhombic insert 11,
 48. 6. A cutting insert according to claim 1, characterized in that the insert 11, 48 has a hole which passes centrally through the flat side surfaces 12, 13 that is disposed to received a pin 27 to secure the insert into clamping engagement with substantially complementary support surfaces of a recess in a holder
 10. 7. A cutting insert according to claim 6, characterized in that the diameter of the centrally disposed hol of the insert is greater than the length of the edge portions 21,
 22. 